Get rid of most instance of 'foo == NULL'

fpdfsdk/src/fxedit/fxet_edit.cpp

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #include "fpdfsdk/include/fxedit/fxet_edit.h"
 #include "fpdfsdk/include/fxedit/fxet_stub.h"
 
 #define FX_EDIT_UNDO_MAXITEM 10000
@@ skipping 796 matching lines @@
       m_bOprNotify(FALSE),
       m_pGroupUndoItem(NULL) {
   ASSERT(pVT);
 }
 
 CFX_Edit::~CFX_Edit() {
   delete m_pVTProvide;
   m_pVTProvide = NULL;
   delete m_pIterator;
   m_pIterator = NULL;
-  ASSERT(m_pGroupUndoItem == NULL);
+  ASSERT(!m_pGroupUndoItem);
 }
 
 // public methods
 
 void CFX_Edit::Initialize() {
   m_pVT->Initialize();
   SetCaret(m_pVT->GetBeginWordPlace());
   SetCaretOrigin();
 }
 
@@ skipping 2254 matching lines @@
   return wp;
 }
 
 int32_t CFX_Edit::GetCharSetFromUnicode(FX_WORD word, int32_t nOldCharset) {
   if (IFX_Edit_FontMap* pFontMap = GetFontMap())
     return pFontMap->CharSetFromUnicode(word, nOldCharset);
   return nOldCharset;
 }
 
 void CFX_Edit::BeginGroupUndo(const CFX_WideString& sTitle) {
-  ASSERT(m_pGroupUndoItem == NULL);
+  ASSERT(!m_pGroupUndoItem);
 
   m_pGroupUndoItem = new CFX_Edit_GroupUndoItem(sTitle);
 }
 
 void CFX_Edit::EndGroupUndo() {
   m_pGroupUndoItem->UpdateItems();
   m_Undo.AddItem(m_pGroupUndoItem);
   if (m_bOprNotify && m_pOprNotify)
     m_pOprNotify->OnAddUndo(m_pGroupUndoItem);
   m_pGroupUndoItem = NULL;
 }
 
 void CFX_Edit::AddEditUndoItem(CFX_Edit_UndoItem* pEditUndoItem) {
   if (m_pGroupUndoItem)
     m_pGroupUndoItem->AddUndoItem(pEditUndoItem);
   else {
     m_Undo.AddItem(pEditUndoItem);
     if (m_bOprNotify && m_pOprNotify)
       m_pOprNotify->OnAddUndo(pEditUndoItem);
   }
 }
 
 void CFX_Edit::AddUndoItem(IFX_Edit_UndoItem* pUndoItem) {
   m_Undo.AddItem(pUndoItem);
   if (m_bOprNotify && m_pOprNotify)
     m_pOprNotify->OnAddUndo(pUndoItem);
 }